1. Field of the Invention
The present invention relates to a power-on function of, for example, a host computer including a universal serial bus (USB) interface, and more particularly to an apparatus for turning on a computer power supply, which is constructed so as to start up the host computer as a result of an operation of an input device, such as a keyboard, when a main power supply of the host computer is in an off state.
2. Description of the Related Art
In conventional computers, pieces of software are built in as resident programs in order to prevent wasteful energy consumption and to increase the efficiency with which energy is saved when the host computer is not used for a long time.
In executing the resident program, when an input operation is not performed within a predetermined period of time from the most recent operation that has been performed at the input device, such as a keyboard, an operation which changes an electrical power mode of the host computer to a suspend mode is carried out. In the suspend mode, the clock speed of a central processing unit (CPU) is reduced, a drive motor of a hard disk or a floppy disk is stopped, and a display is turned off, so that the amount of electrical current supplied to the host computer for consumption is such that the host computer is set in a low electrical power state.
When the host computer is set in the suspend mode, and the input device, such as a keyboard, is operated, the host computer receives information that the input device has been operated. This information is received in the form of a start-up signal. When this start-up signal is input to the host computer, the clock speed of the CPU returns to its original speed, the hard disk or the floppy disk drive motor is started again, and the display is turned on again. Accordingly, the host computer is restored to the state prior to the suspend mode state.
Personal computer peripheral interfaces that have been primarily used for a long time are serial ports (RS232-C) and Centronics parallel ports. However, these types of peripheral interfaces have the following problems. The first problem is that the transfer speed limit is low. The second problem is that a larger number of ports need to be used when connecting a plurality of devices because only one device can be connected to one port. The third problem is that separate ports need to be provided for connecting a keyboard, a mouse, a display, etc., so that various connectors get crowded on the back side of the personal computers.
To overcome the above-described problems, there has been proposed the USB, which allows various peripheral devices to be connected to only one connector as a result of integrating these interfaces. The USB has been rapidly attracting attention as a standard peripheral interface of the next generation.
However, in the above-described conventional computers, the suspend and restore functions are provided on the assumption that the main power supply of the host computer is in an on state. Therefore, when the main power supply is in an off state, the host computer cannot be started with the above-described software.
There has been a demand for adding value to such computers connected with the USB interface by providing a function that the USB does not have, that is, by providing a key called a power-on key, which allows the host computer to be started by a key input operation at a keyboard.
Accordingly, it is an object of the present invention to provide an apparatus for turning on a computer power supply, which is constructed so as to start up a host computer including a USB interface by turning on a main power supply as a result of operating an input device when a switch of the main power supply of the host computer is in an off state.
To overcome the above-described conventional problems, according to a basic form of the present invention, there is provided an apparatus for turning on a computer power supply, comprising a host computer; an input device connected to the host computer through an interface; a main power supply for starting up the host computer; and a sub-power supply for applying electrical power to the input device when the main power supply is in an off state; wherein the host computer comprises wake-up means for turning on the main power supply to start up the host computer as a result of a predetermined operation performed at the input device when the main power supply is in an off state.
According to the present invention, when the switch of the main power supply of the host computer is in an off state, and a keyboard, for example, is operated, the main power supply is turned on to start up the host computer.
To make this operation possible, the sub-power supply (which is a battery) of the host computer supplies electrical power to the input device, such as a keyboard, through the interface. Therefore, when the main power supply of the host computer is in an off state, the electrical power level of the host computer is set low (which is also the case when the host computer is set in its ordinary suspend mode).
When the predetermined operation is performed at the input device, the main power supply is turned on. Here, the operation may be performed on a special-purpose power-on key on the keyboard or on any combination of a plurality of keys. The operation may also be performed on a switch of, for example, a mouse for a predetermined time or a predetermined number of times.
In another form of the present invention, an apparatus for turning on a computer power supply may further comprise switching means disposed at the interface, wherein when the main power supply is in an on state, the switching means connects a signal line of the host computer and a signal line of the input device, and wherein when the main power supply is in an off state, the switching means switches connections so that the wake-up means and the signal line of the input device are connected together; and
wherein when the main power supply is in the off state, and a predetermined operation is performed at the input device, a start-up signal generated by the wake-up means is applied to the main power supply to turn on the main power supply, whereby the switching means switches connections so that the signal line of the host computer and the signal line of the input device are connected together.
The switching means may be, for example, a relay or a logic circuit.
In this case, when the main power supply is in an off state, the wake-up means and the input means, such as a keyboard, are connected together. When, for example, a predetermined key on the keyboard is operated, the main power supply is turned on by the wake-up means to start up the host computer, and the signal line of the host computer and the signal line of the input device are connected together. Therefore, after the host computer has been started, a signal indicating that the input operation has been performed at the keyboard can be transmitted to the host computer.
In still another form of the present invention, when an apparatus for turning on a computer power supply comprises a host computer, an input device connected to the host computer through an interface, a main power supply for starting up the host computer, and a sub-power supply for applying electrical power to the input device when the main power supply is in an off state, and when the host computer comprises wake-up means, the interface may comprise four signal lines, that is, a universal serial bus standard power supply line, a first signal line, a second signal line, and a ground line. In addition, the wake-up means may comprise first comparing means for detecting whether or not a value of the first signal line is equal to or greater than a predetermined standard value, second comparing means for, detecting whether or not a value of the second signal line is equal to or greater than the predetermined standard value, and an AND circuit for determining a logical OR between the first comparing means and the second comparing means, with the main power supply being turned on when the logical OR reaches a predetermined value.
In still another form of the present invention, when the interface comprises four signal lines, that is, a universal serial bus standard power supply line, a first signal line, a second signal line, and a ground line, and when the wake-up means comprises first comparing means, second comparing means, and an AND circuit, the predetermined operation may be performed at the input device in order to output H signals of a predetermined pulse width to both the first signal line and the second signal line, after which the H signals with a predetermined pulse width equal to or greater than the predetermined pulse width are output from the AND circuit to turn on the power supply.
The communication mode in which both of the first signal line and the second signal line are in an H state result from a combination that does not exist in ordinary USB standard operation modes. Therefore, when the wake-up means is constructed so that it starts up when H signals are applied to both of these lines, there is no obstacle to carrying out ordinary communications using the USB interface. When the communication mode is switched at the USB interface, the first signal line and the second signal line may both be instantaneously set in the H state. When the duration in which the first signal line and the second signal line are in the H state becomes equal to or greater than a predetermined time period (more specifically, a time period which is longer than a USB standard signal transfer rate), and an attempt is made to start up the wake-up means, it is possible to prevent confusion with the case where communication modes are switched by the USB interface.
With the first signal line and the second signal line being set in the H state when the main power supply is on and input from the input device is temporarily stopped, the main power supply can be turned off by setting both the first signal line and the second signal line in an L state for a predetermined period of time as a result of carrying out the predetermined operation at the input device.